1. Fieid of the Invention
The invention relates to a system for protecting endoscopes during endoscopic surgical procedures. The invention is particularly suited to protect arthroscopes during arthroscopic surgery. Still more particularly, the invention relates to a disposable sheath adapted to shield the imaging optics at the distal tip of an arthroscope.
2. Description of the Prior Art
Arthroscopic surgical procedures require the use of elongated optical viewing devices (e.g. arthroscopes) and other instruments through one or more openings or portals of the body. Very often in diagnostic and operative arthroscopic surgical procedures an arthroscope is inserted in one portal while an instrument such as a manual or powered resecting instrument is inserted in another portal. The distal ends of the arthroscope and resecting instrument are manipulated by triangulation by the surgeon to resect or otherwise treat tissue at the surgical site.
The terms xe2x80x9cendoscopexe2x80x9d and xe2x80x9carthroscopexe2x80x9d and the like may be used interchangeably herein. While the invention is described in terms of an arthroscope used for arthroscopic surgery, it is equally suited for endoscopic surgery in general where there is an interest in protecting the distal end of the endoscope. The terms xe2x80x9cendoscopexe2x80x9d and xe2x80x9cendoscopic surgeryxe2x80x9d are used herein to refer to all minimally invasive surgical procedures and associated instruments used to access internal surgical sites through natural openings or other portals in a body (human or otherwise). Such procedures may include arthroscopy, laparoscopy, hysteroscopy, etc. While a scope used in these procedures may simply have an eyecup at the proximal end to enable direct observation by a surgeon, preferably the proximal end of the scope is adapted to interface with an image forming device such as a video camera to enable the procedure to be viewed on a monitor.
An arthroscope generally comprises an elongated rigid or flexible tubular shaft containing an optical (i.e. imaging) system aligned along the scope axis to transmit an image of the work site from its distal end to its proximal end. An objective lens or lens group is situated at the distal end of the scope to create an image and an ocular lens or lens group is situated at the proximal end to present the image to an observer through, for example, an interface with an image forming device such as a video camera. While the work site may be illuminated by a light source separate from the scope, preferably the arthroscope is sized to fit coaxially within a lumen of an illuminating sheath or cannula in the form of an elongated tube having open distal and proximal ends. An illuminating cannula contains fiberoptics or other illuminating light transmitting material to direct light from an input port at the proximal end of the illuminating cannula, through the wall of the cannula to its distal end. The arthroscope is concentrically assembled within the illuminating cannula so that the distal ends of both devices are in approximately the same plane and aligned either perpendicular to the concentric axes of the assembled scope and cannula or angled at some predetermined angle relative to the axes. The term xe2x80x9carthroscopexe2x80x9d is sometimes used to refer to the scope portion of the device and sometimes used to refer to both the scope and cannula. In some cases, as for example in U.S. Pat. No. 5,377,669 (Shulz), the arthroscope and illuminating cannula are combined into a single endoscope.
During endoscopic surgery, the close proximity of the distal ends of the scope and the illuminating cannula to manual or powered resection instruments inserted through another portal frequently leads to inadvertent contact and resultant damage of either the optical system or fiberoptics by the resection instrument. Damage of the arthroscope may either destroy it or seriously degrade the image quality necessitating significant repair costs. Damage to the illuminating optics in the fiberoptic cannula is not as costly as damage to the imaging optical system although damage to either component results in less than optimal system performance and unwanted repair costs.
Protection of the distal end of an endoscope is available to some extent by prior art scopes which have interchangeable sheaths. As shown in U.S. Pat. No. 5,573,493 (Sauer et al.), for example, such prior art endoscopic sheaths contain the fiberoptics as well as a prism to change the angle of view. Similar fiberoptic and lens containing (interchangeable) endoscope tips are shown in U.S. Pat. Nos. 4,747,661 (Ohkuwa) and 4,765,313 (Kumakura). While these tips are smaller than the aforementioned interchangeable sheath, they are still relatively costly. While intended to be replaceable, these sheaths and tips contain costly elements and do not efficiently protect the endoscope tip.
Prior art interchangeable sheaths that include fiberoptics result in decreased fiberoptic transmission due to the inefficiency of transmission at the tip interface. Additionally sheaths that cover both the distal tip of the illuminating light path and the imaging optics produce internal reflections (of illuminating light) from the distal face of the sheath, which reflections may stray into the imaging optics and degrade the image.
Prior art sheaths that have optical portions are costly if made from the type of glass which is necessary to achieve high optical performance and efficiency. Therefore, it is difficult, if not simply impractical to make such sheaths disposable. If they were made inexpensively in order to be disposable, they would suffer poor optical performance. Additionally, alignment of the sheath objective portion is difficult to achieve and, consequently, interchangeable tips must be made to tight tolerances that must be maintained to prevent image degradation due to misalignment. This also contributes to increased cost.
It is, therefore, an object of the present invention to produce an endoscope system which protects the optical system of an endoscope, in particular its distal end.
It is a further object of this invention to provide a protection system for protecting the distal tip of an endoscope from inadvertent damage during surgical procedures.
It is an additional object of this invention to provide a protection system for protecting the distal tip of an endoscope from inadvertent damage without compromising the image quality.
It is also an object of this invention to provide an endoscope which may be easily repaired if damaged.
It is yet another object of this invention to produce an endoscope tip protection system adaptable to a variety of endoscope viewing angles.
It is still another object of this invention to produce an endoscope tip protection system which is disposable.
These and other objects of this invention are embodied in an endoscope tip protection system comprising a tubular sheath having an open proximal end, a closed, optically transparent distal end and an internal bore therebetween. The endoscope has a proximal, viewing end and a distal objective end adapted to be received and selectively attached within the internal bore of the sheath. The assembled distal ends of the endoscope and the tubular sheath are adapted to be selectively received within a fiberoptic illumination cannula having an internal bore, an open proximal end and an open distal end.